Framework construction of high coordination carbon nitrogen chelates by classical organic reactions

Professor Zhang Hong and Professor Xia Haiping of the school of chemistry and chemical engineering of Xiamen University have made important development in the field of carbon dragon chemistry Relevant achievements were published in nature communications (NAT Commin 2019, 10, 1488) under the title of "successful modification of polyate complexes gives access toplanar carbon - and nitrogen based lives" Multi tooth chelates with carbon and nitrogen as bonding atoms are very important in the complex family For example, NC chelates with two teeth, NCN chelates with three teeth and CNC / CCN chelates show multiple functions and are widely used in many fields There are relatively few planar NC chelates with higher number of teeth, and the representative ones are tetradentate metalloporphyrins, which have attracted wide attention due to their unique structure and rich physical and chemical properties However, it is difficult to synthesize planar five - and six tooth NC chelates because of their geometry crowding, which has not been reported before In this work, the ccccccn / ncccn planar pentadentate chelates were successfully synthesized by classical organic reaction (insertion reaction of alkyne to metal carbene) The results show that the high reactivity of metal carbene in the ternary ring and the inherent aromaticity of heterocondensed aromatic ring are the key factors to realize this series of transformations The direct conversion of these high coordination chelates has also realized a series of unique reaction types, including the transfer reaction of heteroaromatic units in the dense ring system, the conversion of aromatic skeleton structure, and the change of the aromaticity of metal nitrogen heterocycles This study provides a new idea for the synthesis of high coordination chelates and adds new members to the family of planar pentadentate chelates In particular, these high coordination chelates have good absorption in visible and near infrared regions, showing good photoacoustic imaging, photothermal conversion and acoustic dynamics properties As the first organometallic compound with these three properties, it is expected to develop into a new kind of integrated diagnostic and therapeutic reagent (source: Nat Commun.) the research work was completed under the guidance of Professor Zhang Hong The first author was Zhou Xiaoqian, postdoctoral of I chem This work fully embodies the advantages of multi-disciplinary collaborative research: the synthesis, characterization and theoretical calculation of related compounds were completed by Dr Zhou Xiaoqian; the research on acoustic dynamics was completed by Dr Pang Xin and Professor Liu Gang of School of public health of Xiamen University; the research on photoacoustic imaging was completed by Professor Nie Liming of School of public health of Xiamen University Dr Zhuo Qingde, Dr Zhuo Kaiyue and Dr Chen Zhixin participated in some experiments Professor Xia Haiping, Professor Lin Zhenyang of Hong Kong University of science and technology and Professor Zhu Congqing of Nanjing University gave great support to the research work The work is supported by the National Natural Science Foundation of China, the Hong Kong research funding Bureau, the Fujian Natural Science Foundation and the president's fund of Xiamen University.